Australian Greens immigration spokesperson Senator Sarah Hanson-Young said it was clear that when the new law was introduced the Australian government had no idea how many New Zealanders would end up in detention.

"It's a test for Malcolm Turnbull as he visits New Zealand. Will he fix the problem or will he continue with Tony Abbott's brash, crass and hard over-reach on immigration?"

Ms Hanson-Young said her main concern was for the 100 New Zealanders being detained on Christmas Island.

New Zealand Green Party MP Catherine Delahunty said she hoped Mr Key would make a real effort in this weekend's talks.

"This is happening to us, to Kiwis, and this is happening in our backyard," she said.

"Malcolm Turnbull in his visit to New Zealand needs to be told very clearly that he can't treat - he shouldn't be treating anyone like this, it is all a breach of human rights - but actually, certainly, if he comes here, he should expect to hear a strong message - and we hope our prime minister will step up."

The Labour Party has also said New Zealanders facing deportation in Australia are being treated unfairly and need Mr Key to argue their case.

Protest in Wellington

A small group of protesters marched to Parliament this afternoon to call on Mr Key to demand better treatment for New Zealanders convicted in Australia.

Advocacy group 'Iwi n Aus' organised the protest. A spokesperson, Erina Morunga, said they wanted the two prime ministers to ensure New Zealanders were treated fairly.

"We totally oppose the practices of the Australian government in what they're doing to our people," she said.

"In particular it's because it's a humanity issue. They're mistreating our people and they're basically holding them without a real charge. They've cancelled their visa and they're now abusing them."

Ms Morunga said people in detention centres have done their time in prison and should not be left in limbo.